Animation Nodes - Pressure Arrows / Scaling, Rotating and Changing color along surface
To put arrows pointing along the normals of the vertices of a room, you can sample the vertices normals, convert them to Eulers through the Direction To Rotation Node and use that euler along with the vertices locations ro compose a list of matrices representing the transformations of arrows. Then we you can offset those matrices just as you did implementing the variable scale and rotation, and the color can be set as a vertex color just as you did (Making sure Deep Copy is enabled in the instancer node):